Abstract: To order to achieve the application of synthetic aperture ladar (SAL) in target detection,the characteristics and strong points of SAL in returning wave signal-to-noise ratio(SNR),detecting range,synthetic aperture time and linear frequency modulation orad demodulation were theoretically analyzed based on the signal transmission model and returning wave model.The performances were compared with traditional heterodyne ladar and synthetic aperture radar(SAR).The results show that SAL has higher returning wave SNR and farther detecting range than traditional heterodyne ladar,and the imaging speed is faster than SAR,which benefit the application of SAL on long range target detecting,tracking and fast early warning.